Filed by: malexandru [at] mozilla.com
Parsed log: https://treeherder.mozilla.org/logviewer?job_id=322060554&repo=autoland
Full log: https://firefox-ci-tc.services.mozilla.com/api/queue/v1/task/SPwvcrQdSWa1qj0jD26vMA/runs/0/artifacts/public/logs/live_backing.log

[task 2020-11-17T15:58:08.729Z] 15:58:08     INFO - TEST-OK | /fetch/http-cache/304-update.any.worker.html | took 10280ms
[task 2020-11-17T15:58:08.729Z] 15:58:08     INFO - TEST-START | /fetch/http-cache/304-update.any.html
[task 2020-11-17T15:58:08.730Z] 15:58:08     INFO - Closing window 38
[task 2020-11-17T15:58:08.938Z] 15:58:08     INFO - PID 1545 | JavaScript error: chrome://marionette/content/actors/MarionetteCommandsChild.jsm, line 62: TypeError: can't access property "addEventListener", this.contentWindow is null
[task 2020-11-17T15:58:08.956Z] 15:58:08     INFO - PID 1545 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:10.855Z] 15:58:10     INFO - 
[task 2020-11-17T15:58:10.855Z] 15:58:10     INFO - TEST-UNEXPECTED-FAIL | /focus/focus-restoration-in-different-site-iframes-window.html | Check result - assert_equals: Check log expected "outerlog:log:willfocuswindow,windowfocus,didfocuswindow,windowblur,windowfocus," but got "outerlog:log:willfocuswindow,windowfocus,didfocuswindow,"
[task 2020-11-17T15:58:10.855Z] 15:58:10     INFO - window.onmessage/<@http://web-platform.test:8000/focus/focus-restoration-in-different-site-iframes-window.html:10:22
[task 2020-11-17T15:58:10.855Z] 15:58:10     INFO - Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:2044:25
[task 2020-11-17T15:58:10.855Z] 15:58:10     INFO - test@http://web-platform.test:8000/resources/testharness.js:572:30
[task 2020-11-17T15:58:10.855Z] 15:58:10     INFO - window.onmessage@http://web-platform.test:8000/focus/focus-restoration-in-different-site-iframes-window.html:9:9
[task 2020-11-17T15:58:10.855Z] 15:58:10     INFO - TEST-OK | /focus/focus-restoration-in-different-site-iframes-window.html | took 4398ms
[task 2020-11-17T15:58:10.905Z] 15:58:10     INFO - PID 1535 | 1605628690858	Marionette	INFO	Stopped listening on port 55662
[task 2020-11-17T15:58:11.375Z] 15:58:11     INFO - Browser exited with return code 0
[task 2020-11-17T15:58:11.375Z] 15:58:11     INFO - PROCESS LEAKS None
[task 2020-11-17T15:58:11.379Z] 15:58:11     INFO - Closing logging queue
[task 2020-11-17T15:58:11.380Z] 15:58:11     INFO - queue closed
[task 2020-11-17T15:58:11.413Z] 15:58:11     INFO - Application command: /Users/cltbld/tasks/task_1605628105/build/application/Firefox Nightly.app/Contents/MacOS/firefox --marionette about:blank -foreground -profile /var/folders/lz/t8dchm0j497_vjtzsbt16xn4000017/T/tmp96EMS7
[task 2020-11-17T15:58:11.429Z] 15:58:11     INFO - Starting runner
[task 2020-11-17T15:58:14.084Z] 15:58:14     INFO - PID 1560 | console.warn: SearchSettings: "get: No settings file exists, new profile?" (new Error("", "(unknown module)"))
[task 2020-11-17T15:58:15.806Z] 15:58:15     INFO - PID 1560 | 1605628695738	Marionette	INFO	Listening on port 55784
[task 2020-11-17T15:58:16.089Z] 15:58:16     INFO - PID 1560 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:16.090Z] 15:58:16     INFO - TEST-START | /focus/focus-restoration-in-different-site-iframes.html
[task 2020-11-17T15:58:16.420Z] 15:58:16     INFO - PID 1560 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:18.635Z] 15:58:18     INFO - 
[task 2020-11-17T15:58:18.635Z] 15:58:18     INFO - TEST-PASS | /fetch/http-cache/304-update.any.html | HTTP cache updates returned headers from a Last-Modified 304 
[task 2020-11-17T15:58:18.635Z] 15:58:18     INFO - TEST-UNEXPECTED-FAIL | /fetch/http-cache/304-update.any.html | HTTP cache updates stored headers from a Last-Modified 304 - assert_less_than: Response 3 does not come from cache expected a number less than 3 but got 3
[task 2020-11-17T15:58:18.635Z] 15:58:18     INFO - checkResponse@http://web-platform.test:8000/fetch/http-cache/http-cache.js:145:25
[task 2020-11-17T15:58:18.636Z] 15:58:18     INFO - ...
[task 2020-11-17T15:58:18.636Z] 15:58:18     INFO - TEST-OK | /fetch/http-cache/304-update.any.html | took 9921ms
[task 2020-11-17T15:58:18.712Z] 15:58:18     INFO - PID 1545 | 1605628698644	Marionette	INFO	Stopped listening on port 55732
[task 2020-11-17T15:58:19.229Z] 15:58:19     INFO - Browser exited with return code 0
[task 2020-11-17T15:58:19.229Z] 15:58:19     INFO - PROCESS LEAKS None
[task 2020-11-17T15:58:19.230Z] 15:58:19     INFO - Closing logging queue
[task 2020-11-17T15:58:19.230Z] 15:58:19     INFO - queue closed
[task 2020-11-17T15:58:19.236Z] 15:58:19     INFO - Application command: /Users/cltbld/tasks/task_1605628105/build/application/Firefox Nightly.app/Contents/MacOS/firefox --marionette about:blank -foreground -profile /var/folders/lz/t8dchm0j497_vjtzsbt16xn4000017/T/tmpX2X5GT
[task 2020-11-17T15:58:19.239Z] 15:58:19     INFO - Starting runner
[task 2020-11-17T15:58:21.251Z] 15:58:21     INFO - .
[task 2020-11-17T15:58:21.251Z] 15:58:21     INFO - TEST-OK | /focus/focus-restoration-in-different-site-iframes.html | took 5166ms
[task 2020-11-17T15:58:21.251Z] 15:58:21     INFO - TEST-START | /focus/focus-restoration-in-same-site-iframes-window.html
[task 2020-11-17T15:58:21.256Z] 15:58:21     INFO - Closing window 38
[task 2020-11-17T15:58:21.934Z] 15:58:21     INFO - PID 1560 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:22.242Z] 15:58:22     INFO - PID 1566 | console.warn: SearchSettings: "get: No settings file exists, new profile?" (new Error("", "(unknown module)"))
[task 2020-11-17T15:58:24.085Z] 15:58:24     INFO - PID 1566 | 1605628704072	Marionette	INFO	Listening on port 55811
[task 2020-11-17T15:58:24.392Z] 15:58:24     INFO - PID 1566 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:24.468Z] 15:58:24     INFO - TEST-START | /fetch/http-cache/304-update.any.serviceworker.html
[task 2020-11-17T15:58:24.542Z] 15:58:24     INFO - Setting pref network.http.rcwn.enabled (false)
[task 2020-11-17T15:58:24.551Z] 15:58:24     INFO - Setting pref privacy.partition.network_state (true)
[task 2020-11-17T15:58:24.634Z] 15:58:24     INFO - PID 1566 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:24.761Z] 15:58:24     INFO - PID 1566 | JavaScript error: chrome://marionette/content/actors/MarionetteCommandsChild.jsm, line 62: TypeError: can't access property "addEventListener", this.contentWindow is null
[task 2020-11-17T15:58:24.896Z] 15:58:24     INFO - PID 1566 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:26.703Z] 15:58:26     INFO - 
[task 2020-11-17T15:58:26.704Z] 15:58:26     INFO - TEST-UNEXPECTED-FAIL | /focus/focus-restoration-in-same-site-iframes-window.html | Check result - assert_equals: Check log expected "outerlog:log:willfocuswindow,windowfocus,didfocuswindow,windowblur,windowfocus," but got "outerlog:log:willfocuswindow,windowfocus,didfocuswindow,"
[task 2020-11-17T15:58:26.704Z] 15:58:26     INFO - window.onmessage/<@http://web-platform.test:8000/focus/focus-restoration-in-same-site-iframes-window.html:10:22
[task 2020-11-17T15:58:26.704Z] 15:58:26     INFO - Test.prototype.step@http://web-platform.test:8000/resources/testharness.js:2044:25
[task 2020-11-17T15:58:26.704Z] 15:58:26     INFO - test@http://web-platform.test:8000/resources/testharness.js:572:30
[task 2020-11-17T15:58:26.704Z] 15:58:26     INFO - window.onmessage@http://web-platform.test:8000/focus/focus-restoration-in-same-site-iframes-window.html:9:9
[task 2020-11-17T15:58:26.704Z] 15:58:26     INFO - TEST-OK | /focus/focus-restoration-in-same-site-iframes-window.html | took 5445ms
[task 2020-11-17T15:58:26.713Z] 15:58:26     INFO - Restarting browser for new test group
[task 2020-11-17T15:58:26.741Z] 15:58:26     INFO - PID 1560 | 1605628706736	Marionette	INFO	Stopped listening on port 55784
[task 2020-11-17T15:58:27.188Z] 15:58:27     INFO - Browser exited with return code 0
[task 2020-11-17T15:58:27.188Z] 15:58:27     INFO - PROCESS LEAKS None
[task 2020-11-17T15:58:27.189Z] 15:58:27     INFO - Closing logging queue
[task 2020-11-17T15:58:27.189Z] 15:58:27     INFO - queue closed
[task 2020-11-17T15:58:27.226Z] 15:58:27     INFO - Application command: /Users/cltbld/tasks/task_1605628105/build/application/Firefox Nightly.app/Contents/MacOS/firefox --marionette about:blank -foreground -profile /var/folders/lz/t8dchm0j497_vjtzsbt16xn4000017/T/tmpr2CcDX
[task 2020-11-17T15:58:27.236Z] 15:58:27     INFO - Starting runner
[task 2020-11-17T15:58:29.647Z] 15:58:29     INFO - PID 1573 | console.warn: SearchSettings: "get: No settings file exists, new profile?" (new Error("", "(unknown module)"))
[task 2020-11-17T15:58:30.914Z] 15:58:30     INFO - PID 1573 | 1605628710895	Marionette	INFO	Listening on port 55849
[task 2020-11-17T15:58:31.367Z] 15:58:31     INFO - PID 1573 | JavaScript error: , line 0: NotFoundError: No such JSWindowActor 'MarionetteEvents'
[task 2020-11-17T15:58:31.384Z] 15:58:31     INFO - TEST-START | /css/css-backgrounds/animations/background-color-interpolation.html```

We have a similar intermittent failure, see bug 1642889.
Let's see if we found something in bug 1642889 first.

There is some improvement on focus handling to make it less racing between content processes.

https://wiki.mozilla.org/Bug_Triage#Intermittent_Test_Failure_Cleanup
For more information, please visit auto_nag documentation.